This is the first implementation plan :) that will of course change during the implementation. So this is only the first guideline.
release 1 server create the models
read current location latitude, longitude (will need this to test)
add sample data to the database create services
get data receive product code, latitude and longitude return all prices deploy application to server client enter product code get current location from GPS get product prices from server
release 2 client read barcode server restrict the list to 1km range
release 3 client show stores in a map
release 4 server
add data service client
if product not found add data
